New Pool Owner Questions - CYA, pH, Algae

[JenG13]

Hi Everyone,

I am a brand new pool owner and hoping some experts can provide some guidance on issues I’m having.

I inherited a ~13.5k gallon above ground pool when I purchased my home in February. I opened the pool April 30th and 1.5 months later I still can’t get the water right.

Yellow algae started appearing 1-2 weeks after opening it and I still can’t get rid of it. I’m also now battling a combo of high pH and stubborn CYA levels.

Issues/questions:
1. When I first opened my pool and tested my water, my CYA levels were off the charts (250+ ppm). I’ve drained around 70% of my water - almost 1/2 at once, refilled it all, then maybe 3-4 inches at a time several times. The initial drain got my levels down to about 120ppm, but now they seem to be holding steady around 50-75ppm (different tests vary) despite draining a few inches again. Do I need to get them lower than this? I’ve read mixed guidance, but most commonly read 30-50ppm is ideal. I’ve read CYA can live in your liner. Is that true? By the looks of the pool, the vinyl liner is pretty old.

2. Given the CYA issue, I’ve only been using Cal Hypo for chlorine and shock. My pH and alkalinity levels were very low when I first opened the pool (6.3 pH). I got them both to a good place after a few weeks, but that only lasted about a week and now every test has been pH 8.0-8.5 and 200+ ppm alkalinity for weeks even after adding ph down (I’ve been using sodium bisulfate). I didn’t know that Cal Hypo raises pH until now (ugh - I am not a chemist), so now I’m stumped what to do. If I don’t want to raise pH and I don’t want to raise CYA, what do I do? I was looking at liquid chlorine but I’m unclear if that only temporarily or permanently raises pH.

3. THE MUSTARD ALGAE. Oh my god this stuff is a nightmare. How do I get rid of this devil algae? I’ve brought my FC levels up to 15-20ppm several times, I’ve vacuumed to waste 3x after doing this, added algaecide, sanitized my pool tools, etc. It just won’t go away. Do I need to bring my FC levels even higher since my CYA levels are still a little high? At this point I’m convinced it’s not going away and I need to accept it.

I brought by water to a pool store for my very first test, but since then I’ve been using a Taylor K-2006 test kit and a Water Guru automatic tester (surprisingly accurate except for CYA).

Current Measurements:
FC: 2.3
Combined chlorine: 0
PH: 8.1
Alkalinity: 220
Hardness: 242
CYA: ~75 per Taylor test

Algae photos attached.

 

[Texas Splash]

Welcome to TFP! Good news is you have a K-2006 which is a reliable test kit. Not so sure about the others.

You have the option of going right into the SLAM Process now with that elevated CYA of 80 which would require an SLAM FC level of "31" using liquid chlorine. I would not use the cal-hypo for the SLAM.

Or, you can exchange a bit more water to not only lower the CYA a bit more (i.e. 40-50), but to also rid the water of some of the other products added previously. It's your call. The pH just needs to be somewhere around 7.2-7.5 before you begin the SLAM Process. From that point, follow the SLAM page carefully and you should do well. Remove that ladder now though. They hold algae like crazy. You may want to try and open some of it up f possible and/or inject some chlorine into the parts you cant open.

 

[Texas Splash]

If you do exchange water to lower the CYA some more, be sure to go to the FC/CYA Levels to find out what your new SLAM FC level should be based on the new (lower) CYA.

Also bookmark -----> Pool Care Basics

 

[JenG13]

Thank you!

 

[JenG13]

Welcome to TFP! Good news is you have a K-2006 which is a reliable test kit. Not so sure about the others.

You have the option of going right into the SLAM Process now with that elevated CYA of 80 which would require an SLAM FC level of "31" using liquid chlorine. I would not use the cal-hypo for the SLAM.

Or, you can exchange a bit more water to not only lower the CYA a bit more (i.e. 40-50), but to also rid the water of some of the other products added previously. It's your call. The pH just needs to be somewhere around 7.2-7.5 before you begin the SLAM Process. From that point, follow the SLAM page carefully and you should do well. Remove that ladder now though. They hold algae like crazy. You may want to try and open some of it up f possible and/or inject some chlorine into the parts you cant open.

Thank you!! All the googling I’ve done to try to get rid of the algae and I hadn’t come across this process yet. I will try to lower the CYA a bit more and give this a try. Appreciate the links too!